Polychlorinated azoxy and azobenzenes are potential environmental toxicants resulting from industrial manufacturing and agricultural application of chloroanilide herbicides. In vitro short-term studies conducted in our laboratory have indicated the carcinogenic potential of 3,3',4,4'-tetrachloroazobenzene (TCAB). In order to elucidate the mode of action of TCAB and 3,3',4,4'-tetrachloroazoxybenzene (TCAOB), various pharmacokinetic patterns including distribution, absorption and excretion will be examined. Detailed morphological and biochemical changes in target organ(s) will be studied via electron microscopic examinations and related clinical chemistry data. The metabolic fate of TCAB and TCAOB in intact animals will be also investigated employing high pressure liquid chromatography and gas chromatography-mass spectrometry. Attempts will be made to identify the involvement of biologically active metabolites on the molecular level to the observed toxic actions. Emphasis will be placed upon their covalent interaction to cellular macromolecules (DNA, RNA and proteins) in relation to chemical carcinogenesis. Correlation to the mode of action of 2,3,7,8-tetrachlorodibendibenzo-p-dioxin (TCDD) will be extrapolated.